+++ /dev/null
-
-.. _container_orchestration_in_csit:
-
-Container Orchestration in CSIT
-===============================
-
-Overview
---------
-
-Linux Containers
-~~~~~~~~~~~~~~~~
-
-Linux Containers is an OS-level virtualization method for running
-multiple isolated Linux systems (containers) on a compute host using a
-single Linux kernel. Containers rely on Linux kernel cgroups
-functionality for controlling usage of shared system resources (i.e.
-CPU, memory, block I/O, network) and for namespace isolation. The latter
-enables complete isolation of applications' view of operating
-environment, including process trees, networking, user IDs and mounted
-file systems.
-
-:abbr:`LXC (Linux Containers)` combine kernel's cgroups and support for isolated
-namespaces to provide an isolated environment for applications. Docker
-does use LXC as one of its execution drivers, enabling image management
-and providing deployment services. More information in [lxc]_, [lxcnamespace]_
-and [stgraber]_.
-
-Linux containers can be of two kinds: privileged containers and
-unprivileged containers.
-
-Unprivileged Containers
-~~~~~~~~~~~~~~~~~~~~~~~
-
-Running unprivileged containers is the safest way to run containers in a
-production environment. From LXC 1.0 one can start a full system
-container entirely as a user, allowing to map a range of UIDs on the
-host into a namespace inside of which a user with UID 0 can exist again.
-In other words an unprivileged container does mask the userid from the
-host, making it impossible to gain a root access on the host even if a
-user gets root in a container. With unprivileged containers, non-root
-users can create containers and will appear in the container as the
-root, but will appear as userid <non-zero> on the host. Unprivileged
-containers are also better suited to supporting multi-tenancy operating
-environments. More information in [lxcsecurity]_ and [stgraber]_.
-
-Privileged Containers
-~~~~~~~~~~~~~~~~~~~~~
-
-Privileged containers do not mask UIDs, and container UID 0 is mapped to
-the host UID 0. Security and isolation is controlled by a good
-configuration of cgroup access, extensive AppArmor profile preventing
-the known attacks as well as container capabilities and SELinux. Here a
-list of applicable security control mechanisms:
-
-- Capabilities - keep (whitelist) or drop (blacklist) Linux capabilities,
- [capabilities]_.
-- Control groups - cgroups, resource bean counting, resource quotas, access
- restrictions, [cgroup1]_, [cgroup2]_.
-- AppArmor - apparmor profiles aim to prevent any of the known ways of
- escaping a container or cause harm to the host, [apparmor]_.
-- SELinux - Security Enhanced Linux is a Linux kernel security module
- that provides similar function to AppArmor, supporting access control
- security policies including United States Department of Defense-style
- mandatory access controls. Mandatory access controls allow an
- administrator of a system to define how applications and users can
- access different resources such as files, devices, networks and inter-
- process communication, [selinux]_.
-- Seccomp - secure computing mode, enables filtering of system calls,
- [seccomp]_.
-
-More information in [lxcsecurity]_ and [lxcsecfeatures]_.
-
-**Linux Containers in CSIT**
-
-CSIT is using Privileged Containers as the ``sysfs`` is mounted with RW
-access. Sysfs is required to be mounted as RW due to VPP accessing
-:command:`/sys/bus/pci/drivers/uio_pci_generic/unbind`. This is not the case of
-unprivileged containers where ``sysfs`` is mounted as read-only.
-
-
-Orchestrating Container Lifecycle Events
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-Following Linux container lifecycle events need to be addressed by an
-orchestration system:
-
-1. Acquire - acquiring/downloading existing container images via
- :command:`docker pull` or :command:`lxc-create -t download`.
-
-2. Build - building a container image from scratch or another
- container image via :command:`docker build <dockerfile/composefile>` or
- customizing LXC templates in
- `GitHub <https://github.com/lxc/lxc/tree/master/templates>`_.
-
-3. (Re-)Create - creating a running instance of a container application
- from anew, or re-creating one that failed. A.k.a. (re-)deploy via
- :command:`docker run` or :command:`lxc-start`
-
-4. Execute - execute system operations within the container by attaching to
- running container. THis is done by :command:`lxc-attach` or
- :command:`docker exec`
-
-5. Distribute - distributing pre-built container images to the compute
- nodes. Currently not implemented in CSIT.
-
-
-Container Orchestration Systems Used in CSIT
---------------------------------------------
-
-Current CSIT testing framework integrates following Linux container
-orchestration mechanisms:
-
-- LXC/Docker for complete VPP container lifecycle control.
-
-LXC
-~~~
-
-LXC is the well-known and heavily tested low-level Linux container
-runtime [lxcsource]_, that provides a userspace interface for the Linux kernel
-containment features. With a powerful API and simple tools, LXC enables
-Linux users to easily create and manage system or application
-containers. LXC uses following kernel features to contain processes:
-
-- Kernel namespaces: ipc, uts, mount, pid, network and user.
-- AppArmor and SELinux security profiles.
-- Seccomp policies.
-- Chroot.
-- Cgroups.
-
-CSIT uses LXC runtime and LXC usertools to test VPP data plane performance in
-a range of virtual networking topologies.
-
-**Known Issues**
-
-- Current CSIT restriction: only single instance of lxc runtime due to
- the cgroup policies used in CSIT. There is plan to add the capability into
- code to create cgroups per container instance to address this issue. This sort
- of functionality is better supported in LXC 2.1 but can be done is current
- version as well.
-
-- CSIT code is currently using cgroup to control the range of CPU cores the
- LXC container runs on. VPP thread pinning is defined vpp startup.conf.
-
-Docker
-~~~~~~
-
-Docker builds on top of Linux kernel containment features, and
-offers a high-level tool for wrapping the processes, maintaining and
-executing them in containers [docker]_. Currently it is using *runc*,
-a CLI tool for spawning and running containers according to the
-`OCI specification <https://www.opencontainers.org/>`_.
-
-A Docker container image is a lightweight, stand-alone, executable
-package that includes everything needed to run the container:
-code, runtime, system tools, system libraries, settings.
-
-CSIT uses Docker to manage the maintenance and execution of
-containerized applications used in CSIT performance tests.
-
-- Data plane thread pinning to CPU cores - Docker CLI and/or Docker
- configuration file controls the range of CPU cores the Docker image
- must run on. VPP thread pinning defined vpp startup.conf.
-
-Implementation
---------------
-
-CSIT container orchestration is implemented in CSIT Level-1 keyword
-Python libraries following the Builder design pattern. Builder design
-pattern separates the construction of a complex object from its
-representation, so that the same construction process can create
-different representations e.g. LXC, Docker, other.
-
-CSIT Robot Framework keywords are then responsible for higher level
-lifecycle control of of the named container groups. One can have
-multiple named groups, with 1..N containers in a group performing
-different role/functionality e.g. NFs, Switch, Kafka bus, ETCD
-datastore, etc. ContainerManager class acts as a Director and uses
-ContainerEngine class that encapsulate container control.
-
-Current CSIT implementation is illustrated using UML Class diagram:
-
-1. Acquire
-2. Build
-3. (Re-)Create
-4. Execute
-
-::
-
- +-----------------------------------------------------------------------+
- | RF Keywords (high level lifecycle control) |
- +-----------------------------------------------------------------------+
- | Construct VNF containers on all DUTs |
- | Acquire all '${group}' containers |
- | Create all '${group}' containers |
- | Install all '${group}' containers |
- | Configure all '${group}' containers |
- | Stop all '${group}' containers |
- | Destroy all '${group}' containers |
- +-----------------+-----------------------------------------------------+
- | 1
- |
- | 1..N
- +-----------------v-----------------+ +--------------------------+
- | ContainerManager | | ContainerEngine |
- +-----------------------------------+ +--------------------------+
- | __init()__ | | __init(node)__ |
- | construct_container() | | acquire(force) |
- | construct_containers() | | create() |
- | acquire_all_containers() | | stop() |
- | create_all_containers() | 1 1 | destroy() |
- | execute_on_container() <>-------| info() |
- | execute_on_all_containers() | | execute(command) |
- | install_vpp_in_all_containers() | | system_info() |
- | configure_vpp_in_all_containers() | | install_supervisor() |
- | stop_all_containers() | | install_vpp() |
- | destroy_all_containers() | | restart_vpp() |
- +-----------------------------------+ | create_vpp_exec_config() |
- | create_vpp_startup_config|
- | is_container_running() |
- | is_container_present() |
- | _configure_cgroup() |
- +-------------^------------+
- |
- |
- |
- +----------+---------+
- | |
- +------+------+ +------+------+
- | LXC | | Docker |
- +-------------+ +-------------+
- | (inherited) | | (inherited) |
- +------+------+ +------+------+
- | |
- +----------+---------+
- |
- | constructs
- |
- +---------v---------+
- | Container |
- +-------------------+
- | __getattr__(a) |
- | __setattr__(a, v) |
- +-------------------+
-
-Sequentional diagram that illustrates the creation of a single container.
-
-::
-
- Legend:
- e = engine [Docker|LXC]
- .. = kwargs (variable number of keyword argument)
-
- +-------+ +------------------+ +-----------------+
- | RF KW | | ContainerManager | | ContainerEngine |
- +---+---+ +--------+---------+ +--------+--------+
- | | |
- | 1: new ContainerManager(e) | |
- +-+---------------------------->+-+ |
- |-| |-| 2: new ContainerEngine |
- |-| |-+----------------------->+-+
- |-| |-| |-|
- |-| +-+ +-+
- |-| | |
- |-| 3: construct_container(..) | |
- |-+---------------------------->+-+ |
- |-| |-| 4: init() |
- |-| |-+----------------------->+-+
- |-| |-| |-| 5: new +-------------+
- |-| |-| |-+-------->| Container A |
- |-| |-| |-| +-------------+
- |-| |-|<-----------------------+-|
- |-| +-+ +-+
- |-| | |
- |-| 6: acquire_all_containers() | |
- |-+---------------------------->+-+ |
- |-| |-| 7: acquire() |
- |-| |-+----------------------->+-+
- |-| |-| |-|
- |-| |-| |-+--+
- |-| |-| |-| | 8: is_container_present()
- |-| |-| True/False |-|<-+
- |-| |-| |-|
- |-| |-| |-|
- +---------------------------------------------------------------------------------------------+
- | |-| ALT [isRunning & force] |-| |-|--+ |
- | |-| |-| |-| | 8a: destroy() |
- | |-| |-| |-<--+ |
- +---------------------------------------------------------------------------------------------+
- |-| |-| |-|
- |-| +-+ +-+
- |-| | |
- |-| 9: create_all_containers() | |
- |-+---------------------------->+-+ |
- |-| |-| 10: create() |
- |-| |-+----------------------->+-+
- |-| |-| |-+--+
- |-| |-| |-| | 11: wait('RUNNING')
- |-| |-| |-<--+
- |-| +-+ +-+
- |-| | |
- +---------------------------------------------------------------------------------------------+
- | |-| ALT | | |
- | |-| (install_vpp, configure_vpp) | | |
- | |-| | | |
- +---------------------------------------------------------------------------------------------+
- |-| | |
- |-| 12: destroy_all_containers() | |
- |-+---------------------------->+-+ |
- |-| |-| 13: destroy() |
- |-| |-+----------------------->+-+
- |-| |-| |-|
- |-| +-+ +-+
- |-| | |
- +++ | |
- | | |
- + + +
-
-Container Data Structure
-~~~~~~~~~~~~~~~~~~~~~~~~
-
-Container is represented in Python L1 library as a separate Class with instance
-variables and no methods except overriden ``__getattr__`` and ``__setattr__``.
-Instance variables are assigned to container dynamically during the
-``construct_container(**kwargs)`` call and are passed down from the RF keyword.
-
-There is no parameters check functionality. Passing the correct arguments
-is a responsibility of the caller.
-
-Examples
-~~~~~~~~
-
-This section contains a high-level example of multiple initialization steps
-via ContainerManager; taken from an actual CSIT code,
-but with non-code lines (comments, Documentation) removed for brevity.
-
-:
-
-.. code-block:: robotframework
-
- | Start containers for test
- | | [Arguments] | ${dut}=${None} | ${nf_chains}=${1} | ${nf_nodes}=${1}
- | | ... | ${auto_scale}=${True} | ${pinning}=${True}
- | |
- | | Set Test Variable | @{container_groups} | @{EMPTY}
- | | Set Test Variable | ${container_group} | CNF
- | | Set Test Variable | ${nf_nodes}
- | | Import Library | resources.libraries.python.ContainerUtils.ContainerManager
- | | ... | engine=${container_engine} | WITH NAME | ${container_group}
- | | Construct chains of containers
- | | ... | dut=${dut} | nf_chains=${nf_chains} | nf_nodes=${nf_nodes}
- | | ... | auto_scale=${auto_scale} | pinning=${pinning}
- | | Acquire all '${container_group}' containers
- | | Create all '${container_group}' containers
- | | Configure VPP in all '${container_group}' containers
- | | Start VPP in all '${container_group}' containers
- | | Append To List | ${container_groups} | ${container_group}
- | | Save VPP PIDs
-
-Kubernetes
-~~~~~~~~~~
-
-For the future use, Kubernetes [k8sdoc]_ is implemented as separate library
-``KubernetesUtils.py``, with a class with the same name. This utility provides
-an API for L2 Robot Keywords to control ``kubectl`` installed on each of DUTs.
-One time initialization script, ``resources/libraries/bash/k8s_setup.sh``
-does reset/init kubectl, and initializes the ``csit`` namespace. CSIT
-namespace is required to not to interfere with existing setups and it
-further simplifies apply/get/delete Pod/ConfigMap operations on SUTs.
-
-Kubernetes utility is based on YAML templates to avoid crafting the huge
-YAML configuration files, what would lower the readability of code and
-requires complicated algorithms.
-
-Two types of YAML templates are defined:
-
-- Static - do not change between deployments, that is infrastructure
- containers like Kafka, Calico, ETCD.
-
-- Dynamic - per test suite/case topology YAML files.
-
-Making own python wrapper library of ``kubectl`` instead of using the
-official Python package allows to control and deploy environment over
-the SSH library without the need of using isolated driver running on
-each of DUTs.
-
-Tested Topologies
-~~~~~~~~~~~~~~~~~
-
-Listed CSIT container networking test topologies are defined with DUT
-containerized VPP switch forwarding packets between NF containers. Each
-NF container runs their own instance of VPP in L2XC configuration.
-
-Following container networking topologies are tested in |csit-release|:
-
-- LXC topologies:
-
- - eth-l2xcbase-eth-2memif-1lxc.
- - eth-l2bdbasemaclrn-eth-2memif-1lxc.
-
-- Docker topologies:
-
- - eth-l2xcbase-eth-2memif-1docker.
- - eth-l2xcbase-eth-1memif-1docker
-
-References
-~~~~~~~~~~
-
-.. [lxc] `Linux Containers <https://linuxcontainers.org/>`_
-.. [lxcnamespace] `Resource management: Linux kernel Namespaces and cgroups <https://www.cs.ucsb.edu/~rich/class/cs293b-cloud/papers/lxc-namespace.pdf>`_.
-.. [stgraber] `LXC 1.0: Blog post series <https://stgraber.org/2013/12/20/lxc-1-0-blog-post-series/>`_.
-.. [lxcsecurity] `Linux Containers Security <https://linuxcontainers.org/lxc/security/>`_.
-.. [capabilities] `Linux manual - capabilities - overview of Linux capabilities <http://man7.org/linux/man-pages/man7/capabilities.7.html>`_.
-.. [cgroup1] `Linux kernel documentation: cgroups <https://www.kernel.org/doc/Documentation/cgroup-v1/cgroups.txt>`_.
-.. [cgroup2] `Linux kernel documentation: Control Group v2 <https://www.kernel.org/doc/Documentation/cgroup-v2.txt>`_.
-.. [selinux] `SELinux Project Wiki <http://selinuxproject.org/page/Main_Page>`_.
-.. [lxcsecfeatures] `LXC 1.0: Security features <https://stgraber.org/2014/01/01/lxc-1-0-security-features/>`_.
-.. [lxcsource] `Linux Containers source <https://github.com/lxc/lxc>`_.
-.. [apparmor] `Ubuntu AppArmor <https://wiki.ubuntu.com/AppArmor>`_.
-.. [seccomp] `SECure COMPuting with filters <https://www.kernel.org/doc/Documentation/prctl/seccomp_filter.txt>`_.
-.. [docker] `Docker <https://www.docker.com/what-docker>`_.
-.. [k8sdoc] `Kubernetes documentation <https://kubernetes.io/docs/home/>`_.
Code Review / csit.git / blobdiff